1. Field of the Invention
This invention relates to a thermosetting resin composition having excellent heat resistance and high-temperature mechanical properties.
2. Description of the Prior Art
In order to seal electronic components such as diodes, transisters and integrated circuits, resin seal making use of a thermosetting resin has been used widely to date because the resin seal has been economically advantageous over hermetic seal making use of a glass, metal or ceramics. As the resin sealing materials, epoxy resins suitable for use in low-pressure molding may generally be used from the viewpoints of reliability and cost. The epoxy moding materials useful for the low-pressure molding are prepared by mixing a novolak phenol resin as a hardener, 1,4-diazabicyclo[2,2,2]-octane or imidazol as a hardening accelerator, silica powder or alumina powder as a filler, etc. with a novolak cresol- or novolak phenol-epoxy resin and then heating and kneading them. These molding material are separately preheated as tablets. Thereafter, an insert is set in a mold, and its corresponding insoluble and infusible molded articles for electronic components are made from the tablets in accordance with the transfer molding, cast molding or dip molding.
These molding materials are however accompanied by the drawbacks that they are insufficient in heat resistance as the densification of electronic components advances and are hence poor in reliability.